Glycoprotein Ib (hereafter, GPIb) and glycoprotein VI (hereafter, GPVI) exist on a platelet membrane and play important roles each as a von Willebrand factor (hereafter, vWF) receptor and a collagen receptor in case of forming pathologic thrombus as can be found in a region of arteriosclerosis (non-patent document 1). Collagen is exposed by vascular endothelium damage in case of plaque rupture at the arteriosclerosis region, and a high shearing stress is caused by angiostenosis. The vWF tends to be solid-phased on the exposed collagen, and the platelet accumulates and sticks on the arteriosclerosis region by being connected with the vWF on the solid-phased collagen via the GPI. Thereafter, the GPVI on the platelet combines with the collagen, and the platelet is activated and accumulated to induce pathologic thrombus causing ischemic heart disease such as myocardial infarction, ischemic stroke, peripheral arterial obstruction (non-patent document 2). Haemostasis as a defence mechanism of organisms is formed via activation of the platelet by a tissue factor or a soluble agonist (thromboxane A2 (TXA2), adenosine 2 phosphate (ADP), etc.) released from the extravascular damaged-region. Since aspirin and clopidogrel, as existing medicines, have great influences on the hemostasis mechanism and inhibit the functions of TAXA2 and ADP, they enhance the antithrombotic function as well as the hemorrhagic function (non patent document 3). According to the results of the ATT (Antithrombotic Trialists' Collaboration) which was obtained by the meth-analysis of the Randomized Controlled Trial (RCT) of the preventing effect by the existing antiplatelet agent (single administration of aspirin, ticlopidine, etc.), therapeutic reduction effect of the cardiovascular event by the existing antiplatelet agent is at most 25%, and the degree of satisfaction is not high (non patent document 4). Clinical study of the combined therapy was conducted by using conventional antiplatelet agents (CURE, MATCH, CHARISMA) aiming at a higher therapeutic effect, but it was shown that a risk for bleeding also increases (non patent documents: 5-7).
Heterocyclic compounds such as benzimidazole derivatives are disclosed in patent documents 1-13, and in a non-patent document 8. However, these compounds have not been reported to provide an antiplatelet function, and their characteristics are different from those of the compounds of the present invention. Heterocyclic compounds which have a platelet aggregation inhibitory action are disclosed in the document 14. However, their characteristics are different from those of the compounds of the present invention.
The preparation process of benzimidazole derivatives are disclosed in non-patent document 8.